For filtered back-projection of a projection image data set, the projection image data set is cosine-weighted. The cosine-weighted projection image data set within the image plane of the projection image data set is subjected to a two-dimensional Radon transformation. The Radon transform of the cosine-weighted projection image data set differentiated with respect to the distance from an image origin of an image coordinate system. The derivative of the Radon transform is redundancy-weighted. The redundancy-weighted derivative is subjected to a two-dimensional Radon back-transformation. The Radon back-transform is differentiated and back-projected with respect to an image column coordinate. A differentiation step width entering into the differentiation is varied depending on depth.
